engleski

Local Molecular Dynamics in Polyisoprene-Zeolite Composites

Zeolites are often used as fillers for various polymeric materials. Due to their specific structure, they can improve mechanical properties and therefore they are often used as reinforcing agents. The second reason for their possible application is that they react as flame retardants. In this work, zeolites were dispersed in the natural rubber latex which was then irradiated in a 60Co γ-source in order to get a tridimensional network structure. Two types of zeolites were used as fillers: zeolite X and zeolite A. The aim of this work was to investigate how the presence of zeolites affects the local motional behavior of polyisoprene chains. This is particularly important, since the mechanical properties of materials are highly influenced by molecular dynamics. Electron spin resonance (ESR) – spin probe method, known as powerful tool in studying local molecular motions, was used to characterize the chain dynamics of polyisoprene in the presence of zeolites. 4-hydroxi-2, 2, 6, 6-tetramethylpiperidine-1-oxyl was used as a spin probe. Spin probe was incorporated in samples using chloroform and toluene, at temperatures of 40 °C and 60 °C. The difference in motional behavior between the samples containing zeolite X and zeolite A was found and discussed. Zeolite X showed a higher influence on the restriction of local segmental motions and consequently, it seems to be better candidate as a possible reinforcing agent. An influence of the temperature and solvent used during the probe incorporation process was observed and discussed. Acknowledgements This work has been fully supported by Croatian Science Foundation under the project No. 1108, “Low temperature dynamics of systems exhibiting lattice disorder probed by ESR”. References 1. S. Valić, in: Rubber Nanocomposites: Preparation, Properties and Application (Eds.: S. Thomas, R. Stephen), 1st ed., John Wiley & Sons, Singapore, Singapore, 2010. 2. Z. Veksli, M. Andreis, B. Rakvin, Prog. Polym. Sci. 2000, 25, 949-986. 3. M. Didović, D. Klepac, S. Valić, Macromol. Symp. 2008, 265, 144-147. 4. I. Dubrović, D. Klepac, S. Valić, G. Žauhar, Radiat. Phys. Chem. 2008, 77, 811-817.

Natural rubber; zeolite; composite; dynamics

This work has been fully supported by Croatian Science Foundation under the project No. 1108, “Low temperature dynamics of systems exhibiting lattice disorder probed by ESR”.